Apparatus and methods for selecting light emitters

ABSTRACT

Provided are devices and methods for grouping light emitters and devices including the same. Embodiments of such methods may include selecting a portion of the light emitters using a region of a multiple axis color space that is configured to represent each of a plurality of colors as at least two chromaticity coordinates. The region may be proximate a predefined point on the multiple axis color space and includes a major axis having a first length and a minor axis having a second length that is less than the first length.

RELATED APPLICATIONS

This application is a continuation in part of U.S. patent applicationSer. No. 11/940,437, filed on Nov. 15, 2007, in the United States Patentand Trademark Office, the disclosure of which is incorporated herein inits entirety by reference.

FIELD OF THE INVENTION

The present invention relates to lighting, and more particularly toselecting lighting components used in devices.

BACKGROUND

Panel lighting devices are used for a number of lighting applications. Alighting panel may be used, for example, as a backlighting unit (BLU)for an LCD display. Backlighting units commonly rely on an arrangementof multiple light emitters such as fluorescent tubes and/or lightemitting diodes (LED). An important attribute of the multiple lightemitters may include uniformity of color and/or luminance in displayedoutput. Presently, light emitters may be tested and grouped and/orbinned according to their respective output and/or performance toimprove relative uniformity among multiple light emitters. The groupingmay be performed using, for example, chromaticity values, such as thex,y values used in the CIE 1931 color space that was created by theInternational Commission on Illumination in 1931. In this manner, eachlight emitter may be characterized by x,y coordinates. Emitters havingsimilar x,y values may be grouped or binned to be used together.However, emitters having similar x,y coordinates and/or luminosity mayinclude significantly different spectral power distributions that mayadversely impact uniformity when used in conjunction with othercomponents in a device.

SUMMARY

Some embodiments of the present invention include methods for grouping aplurality of light emitters. Some embodiments of methods may includeselecting a portion of the light emitters using a region of a multipleaxis color space that is configured to represent each one of multiplecolors as at least two chromaticity coordinates, the region proximate apredefined point on the multiple axis color space. The region mayinclude a major axis including a first length and a minor axis includinga second length that is less than the first length.

In some embodiments, the multiple axis color space includesInternational Commission on Illumination (CIE) 1976. In someembodiments, the region includes an elliptical, rectangular and/orhexagonal geometry. Some embodiments provide that the major axis isoriented substantially 10 degrees clockwise from a vertical axis of themultiple axis color space. In some embodiments, a ratio of the firstlength to the second length is in range from 1.3 to 2.3. In someembodiments, a ratio of the first length to the second length comprisesapproximately 2.1.

Some embodiments include selecting a plurality of portions of theplurality of light emitters using a plurality of adjacent regions. Insome embodiments, each of the regions includes a substantially similargeometry, orientation and size. Some embodiments include selecting theportion of the light emitters as a function of an application specifictransmission characteristic. In some embodiments, the applicationspecific transmission characteristic includes a transmissioncharacteristic of a display panel.

Some embodiments include generating emitter spectral power distributiondata for each of the light emitters and selecting one of multipleadjacent regions corresponding to the emitter spectral powerdistribution of each of the light emitters. In some embodiments, thelight emitters include solid-state light emitters, incandescent lightsand/or cold-cathode fluorescent lights.

Some embodiments include a computer program product for grouping aplurality of light emitters, the computer program product comprising acomputer usable storage medium having computer readable program codeembodied in the medium, the computer readable program code configured tocarry out the methods described herein.

Some embodiments of the present invention include a device that mayinclude multiple light emitters including a chromaticity differencemaximum defined by a region of a multiple axis color space that isconfigured to represent each of a plurality of colors as at least twochromaticity coordinates. In some embodiments, the region is proximate apredefined point on the multiple axis color space and includes a majoraxis including a first length and a minor axis including a second lengththat is less than the first length.

In some embodiments, the multiple axis color space includes one ofInternational Commission on Illumination (CIE) 1976 and CIE 1931. Insome embodiments, the region includes an elliptical, rectangular and/orhexagonal geometry. In some embodiments, the major axis is orientedsubstantially 10 degrees clockwise from a vertical axis of the multipleaxis color space. In some embodiments, a ratio of the first length tothe second length is in range from 1.3 to 2.3. Some embodiments providethat a ratio of the first length to the second length comprisesapproximately 2.1.

In some embodiments, multiple portions of the light emitters include achromaticity difference maximum defined by respective ones of multipleadjacent regions of the multiple axis color space. Some embodimentsprovide that each of the re-ions includes a substantially similargeometry, orientation and size. In some embodiments, a portion of thelight emitters further include a maximum chromaticity difference definedas a function of an application specific transmission characteristic. Insome embodiments, the application specific transmission characteristicincludes a transmission characteristic of a display panel.

In some embodiments, each of the light emitters includes spectral powerdistribution data and is grouped into one of multiple regionscorresponding to the spectral power distribution data. In someembodiments, the light emitters include solid-state light emitters,incandescent lights and/or cold-cathode fluorescent lights.

Some embodiments of the present invention include apparatus for groupingmultiple light emitters. Apparatus according to some embodiments mayinclude a chromaticity module that is configured to estimate thespectral data corresponding to each of the plurality of light emittersand a color space region definition module that is configured to defineboundaries of a color space region of a multiple axis color space thatis configured to represent each of multiple colors as at least twochromaticity coordinates. Some embodiments provide that the color spaceregion includes a major axis including a first length and a minor axisincluding a second length that is less than the first length. Apparatusaccording to some embodiments may include a selection module that isconfigured to select a portion of the light emitters that correspond tothe color space region.

Some embodiments include means for estimating front of screen (FOS)spectral data corresponding to each of the light emitters, wherein theselection module is configured to select the portion of the lightemitters that correspond to the color space region via the FOS spectraldata.

Some embodiments of the present invention include methods of groupingmultiple light emitters. Such methods may include generating emitter rawspectral power distribution data for each of the light emitters,estimating front of screen (FOS) spectral power distribution data froman application specific transmission characteristic and the emitter rawspectral power data for each of the light emitters, and grouping each ofthe light emitters into one of multiple regions of a multiple axis colorspace that is configured to represent each of multiple colors as atleast two chromaticity coordinates corresponding to the FOS spectralpower distribution data of each of the plurality of light emitters. Someembodiments provide that the region includes a major axis including afirst length and a minor axis including a second length that is lessthan the first length, such that the major axis oriented substantiallydifferent from a vertical axis of the multiple axis color space.

In some embodiments, the major axis is oriented substantially 10 decreesclockwise from the vertical axis of the multiple axis color space. Insome embodiments, a ratio of the first length to the second length is inrange from 1.3 to 2.3. Some embodiments provide that a ratio of thefirst length to the second length comprises approximately 2.1.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate certain embodiment(s) of theinvention.

FIG. 1 is a schematic diagram of a side view illustrating a plurality oflight emitters configured to transmit light to one or more transmissivecomponents according to some embodiments of the present invention.

FIGS. 2A and 2B are schematic color space chromaticity diagramsillustrating a shift in chromaticity resulting from a transmissivecomponent as illustrated in FIG. 1 according to some embodiments of thepresent invention.

FIG. 3 is a schematic color space chromaticity diagram illustratingemitters having same chromaticity coordinates and different spectralcontent according to some embodiments of the present invention.

FIGS. 4A and 4C are schematic spectral power distribution graphs ofpoints illustrated in FIG. 3 before and after application a filterfunction, as illustrated in FIG. 4B, according to some embodiments ofthe present invention.

FIGS. 5A and 5B are block diagrams illustrating systems and/oroperations for applying a filter function to light emitter chromaticitydata according to some embodiments of the present invention.

FIG. 6 is a block diagram illustrating operations for controlling lightemission characteristics in a display panel according to someembodiments of the present invention.

FIG. 7 is a block diagram illustrating operations for selecting multiplelight emitters according to some embodiments of the present invention.

FIG. 8 is a block diagram illustrating operations for generatingfiltered chromaticity data according to some embodiments of the presentinvention.

FIG. 9 is a block diagram illustrating operations for increasing displayuniformity according to some embodiments of the present invention.

FIG. 10 is a schematic diagram of a side view of a device according tosome embodiments of the present invention.

FIG. 11 is a schematic diagram of a side view of a device according toother embodiments of the present invention.

FIG. 12 is a schematic diagram of a side view of a device according toyet other embodiments of the present invention.

FIG. 13 is a block diagram illustrating an apparatus for selecting lightemitters based on intended use according to some embodiments of thepresent invention.

FIG. 14 is a block diagram illustrating operations for grouping lightemitters according to some embodiments of the present invention.

FIG. 15 is a block diagram illustrating operations for grouping lightemitters according to some embodiments of the present invention.

FIGS. 16A-C are schematic graphs illustrating regions in a multiple axiscolor space according to some embodiments of the present invention.

FIG. 17 is a schematic graph illustrating multiple adjacent regions in amultiple axis color space according to some embodiments of the presentinvention.

FIG. 18 is a block diagram illustrating an apparatus for grouping lightemitters according to some embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Embodiments of the present invention now will be described more fullyhereinafter with reference to the accompanying drawings, in whichembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present invention. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” may be used herein to describe a relationshipof one element, layer or region to another element, layer or region asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”“comprising,” “includes” and/or “including” when used herein, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

The present invention is described below with reference to flowchartillustrations and/or block diagrams of methods, systems and computerprogram products according to embodiments of the invention. It will beunderstood that some blocks of the flowchart illustrations and/or blockdiagrams, and combinations of some blocks in the flowchart illustrationsand/or block diagrams, can be implemented by computer programinstructions. These computer program instructions may be stored orimplemented in a microcontroller, microprocessor, digital signalprocessor (DSP), field programmable gate array (FPGA), a state machine,programmable logic controller (PLC) or other processing circuit, generalpurpose computer, special purpose computer, or other programmable dataprocessing apparatus such as to produce a machine, such that theinstructions, which execute via the processor of the computer or otherprogrammable data processing apparatus, create means for implementingthe functions/acts specified in the flowchart and/or block diagram blockor blocks.

These computer program instructions may also be stored in a computerreadable memory that can direct a computer or other programmable dataprocessing apparatus to function in a particular manner, such that theinstructions stored in the computer readable memory produce an articleof manufacture including instruction means which implement thefunction/act specified in the flowchart and/or block diagram block orblocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions which execute on the computer or other programmableapparatus provide steps for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks. It is to beunderstood that the functions/acts noted in the blocks may occur out ofthe order noted in the operational illustrations. For example, twoblocks shown in succession may in fact be executed substantiallyconcurrently or the blocks may sometimes be executed in the reverseorder, depending upon the functionality/acts involved. Although some ofthe diagrams include arrows on communication paths to show a primarydirection of communication, it is to be understood that communicationmay occur in the opposite direction to the depicted arrows.

Reference is now made to FIG. 1, which is a schematic side viewillustrating a plurality of light emitters configured to transmit lightto and/or through one or more transmissive components according to someembodiments of the present invention. Multiple light emitters 100 areconfigured to emit unfiltered light 102 into a cavity towards one ormore transmissive components 120. It will be understood thattransmissive components, as described herein, include components thatmay be partially and/or fully transmissive. Filtered light 122 isemitted from the transmissive components and includes the spectralcharacteristics of the unfiltered light 102 as modified by a filteringeffect of one or more transmissive components 120. In some embodiments,some of the unfiltered light 102 that reaches one or more transmissivecomponents 120 may partially reflect and/or scatter back into the cavity125. The reflected light may be further reflected back into thetransmissive components 120 as recycled unfiltered light (not shown) andmay give rise to additional filtered light 122 from the transmissivecomponents 120.

Light emitters 100 according to some embodiments may include, forexample, cold cathode fluorescent lamps and/or solid state lightemitters, such as, for example, white light emitting LED's, amongothers. In some embodiments, the light emitters 100 may include whiteLED lamps that include a blue-emitting LED coated with a fluorescingcompound that may modify the wavelength of light that is emitted fromthe blue light emitting LED. In some embodiments, the fluorescingcompound may include a wavelength conversion phosphor that converts someof the blue light emitted by the LED into yellow light. The resultinglight, which is a combination of blue light and yellow light, may appearwhite to an observer.

In some embodiments, light emitters 100 may include an array of solidstate lamps such that at least two of the solid state lamps areconfigured to emit light having substantially different dominantwavelengths. In some embodiments, an array of solid state emitters mayinclude quaternary and/or tertiary additive complementary emittercombinations. For example, in some embodiments, an array of solid statelamps may include red, green and blue light emitting devices. When red,green and blue light emitting devices are energized simultaneously, theresulting combined light may appear white, or nearly white, depending onthe relative intensities of the red, green and blue sources. In someembodiments, an array of solid state emitters may include binarycomplementary emitters such as, for example, cyan and orange lightemitters.

The transmissive component 120 may include one or more layers of activeand/or passive optically transmissive materials and/or components. Forexample, an active transmissive component 120 may include an LCDdisplay. LCD displays may include those typically found in LCDtelevisions, monitors, laptop computers, and/or other electronic devicesincluding cell phones, PDA's, personal media players and/or gamingconsoles, among others. In some embodiments, the transmissive component120 may include passive optical elements including, but not limited todiffusing and/or refracting, devices, among others.

Although discussed in the context of LCD devices, a transmissivecomponent 120 as discussed herein is not so limited. For example, atransmissive component 120 may generally include an array of opticalshutters that may be used with a backlight system that impinges light onthe display screen. As is well known to those having skill in the art,an LCD display generally includes an array of liquid crystal devicesthat act as an array of optical shutters. Transmissive LCD displaysemploy backlighting using, for example, fluorescent cold cathode tubes,among others, above, beside and sometimes behind the array of LCDdevices. A diffusion panel behind the LCD devices can be used toredirect and scatter the light evenly to provide a more uniform display.In some embodiments, a transmissive component 120 may include a colorimage such as a photograph, artwork, and/or other transmissive staticgraphic image such as those that may be used in the context of signs,advertisements, and/or vehicular instrument clusters, among others.

In some embodiments, an LCD display may include groups of pixels used toelectronically generate patterns that may be organized into images. Apixel may include a group of multiple subpixels that may each bear afilter and an addressable LCD element that acts as a field-dependentvariable density filter. The filters corresponding to each subpixelmodify the white light prior to its passage into the LCD element bynarrowing the spectral bandwidth of the light. In this manner, whitelight from a bulk area source may be rendered as discrete addressable,variable grayscale, colored subpixels.

In applications where more than one light emitter 100 is needed toachieve sufficient luminous flux in a uniformly distributed fashion,light emitters 100 may be characterized according to performanceproperties and physically sorted into predetermined groups and/or bins.For example, the light emitters 100 may be sorted according tochromaticity and/or luminosity values in order to achieve an acceptabledifference among light emitters 100. Although several of the embodimentsdescribed herein are presented in the context of chromaticity values,luminosity values are also relevant for the same reasons as thechromaticity values, albeit to a lesser degree. If the light emitters100 are sorted based on unfiltered light 102 alone, however, adifference of chromaticity and/or luminosity values of the filteredlight 122 may be greater than that of a difference of chromaticityand/or luminosity values of the unfiltered light 102 as a result of aconvolution filtering effect of the transmissive component 120 on thespectra of the unfiltered light 102. Thus, according to embodimentsherein, the light emitters 100 may be sorted, grouped and/or binnedaccording to chromaticity and/or luminosity of filtered light 122. Inthis regard, the uniformity of the display may be improved by factoringin the effect of the transmissive component 120 in the selection and/orgrouping of the light emitters 100.

As applied herein and, specifically, to chromaticity and/or luminosity,the term “difference” may include a variety of techniques that may beused to describe variation among data values including an arithmeticdifference, statistical variance, standard deviation, maximum and/orminimum ranges among others. In some embodiments, a difference may beestimated as the greatest of the differences between each of thechromaticity and/or luminosity coordinates of the multiple emitters andthe average of the chromaticity and/or luminosity coordinates of all ofthe multiple emitters.

Reference is now made to FIGS. 2A and 2B, which are schematic colorspace chromaticity diagrams illustrating a shift in chromaticityresulting from a transmissive component, as illustrated in FIG. 1,according to some embodiments of the present invention. The human eyeincludes receptors corresponding to the three colors red, green andblue. A graphical device for associating three numbers (tristimulusvalues) with each color is called a color space. A mathematicallydefined color space known as CIE 1931 color space defines color in termsof chromaticity. Luminance may be represented by Y, which isapproximately correlative of the brightness. Chromaticity may beexpressed in terms of x,y parameters, which may be computed using thethree tristimulus values. The tristimulus values X, Y and Z may roughlycorrespond to red, green and blue.

Referring to FIG. 2A, a chromaticity diagram 130 includes an outerboundary that is the spectral locus. Chromaticity of emitted light, suchas the unfiltered light 102 of FIG. 1, may be characterized in terms ofan x,y coordinate pair. For example, point P may represent thechromaticity of the unfiltered light 102.

Referring to FIG. 2B, the chromaticity of Filtered light 122 of FIG. 1may be different than that of unfiltered light 102 due to a filteringeffect of a transmissive component 120. The chromaticity value offiltered light 122 may be characterized in terms of a differentcoordinate pair, x′,y′, illustrated as point P′. In this regard, thechromaticity of the filtered light 122 is dependent on both the spectralcontent of the unfiltered light 102 and the filtering properties of thetransmissive component 122. In the context of multiple light emitters,the chromaticity shift corresponding to the filtering effect is unlikelyto be uniform, or even similar, among different ones of the lightemitters.

The lack of uniformity in the chromaticity shift may be attributed tothe limited information content of the chromaticity x,y values. Forexample, the chromaticity x,y values do not provide for distinctionsbetween spectral power distributions among different emitters.

Reference is now made to FIG. 3, which is a schematic color spacechromaticity diagram illustrating emitters having same chromaticitycoordinates and different spectral content according to some embodimentsof the present invention. The chromaticity diagram 130 illustrates asimplistic representation of two light emitters A and B havingchromaticity x,y values corresponding to point P. As illustrated, lightemitter A may include spectral power distribution bands correlating tochromaticity (color) values A1 and A2, which, when combined, yieldchromaticity x,y values corresponding to P. Light emitter B includesspectral distribution bands corresponding to chromaticity values B1 andB2, which, when combined, yield chromaticity x,y values that alsocorrespond to P. Note that emitters A and B have dramaticallydistinctive spectral content and yet are characterized by the samechromaticity x,y values at point P. Thus, although light emitters A andB are perceived as the same when viewed directly, they includesignificantly different spectral content.

The phenomenon illustrated in FIG. 3 may be termed as source metamerism.Metamerism describes the circumstance where two color sources havingdifferent spectral power distributions appear to be the same color whenviewed side by side. The metamerism occurs because each of the threetypes of human eye receptors responds to the cumulative energy from abroad range of wavelengths. In this regard, many different combinationsof light across all wavelengths can produce an equivalent receptorresponse and the same tristimulus values. Thus, two spectrally differentcolor samples may visually match and be characterized by the samechromaticity values.

Reference is now made FIGS. 4A and 4C, which are schematic spectralpower distribution graphs of points illustrated in FIG. 3 before andafter application of a filter function, as illustrated in FIG. 4B,according to some embodiments of the present invention. Referring toFIG. 4A, as discussed above regarding FIG. 3, a light emitter A mayinclude spectral emissions A1 and A2 that occur at substantiallydifferent wavelengths. Similarly, light emitter B may include spectralemissions B1 and B2 that occur at substantially different wavelengthsfrom each other and from spectral emissions A1 and A2. In this regard,although light emitters A and B may be characterized by the samechromaticity x,y values at P, they have distinctly different spectralpower distributions.

Referring to FIG. 4B, a transmissive component, such as, for example, anLCD display, may effectively apply a filtering operation that is simplyillustrated as a transmittance plot 150 including high transmissionportions 152 corresponding to some wavelengths of light and a lowtransmission portion 154 corresponding to other wavelengths of light. Insome embodiments, the LCD display may include an LCD cell, a colorfilter array, one or more polarizers, and/or other transmissivecomponents, among others. In this regard, as illustrated in FIG. 4C,when light emitted from light emitter A is transmitted through thetransmissive component, the resulting light is effectively the same inspectral content as the emitted light because the peak of spectralemissions A1 and A2 are coincident with the high transmission portions152 of the transmittance plot 150.

In contrast, when light emitted from light emitter B is transmittedthrough the transmissive component, the peak of spectral emission B1 iscoincident with the low transmission portion 154 and the peak ofspectral emission B2 is coincident with a high transmission portion 152.The B1 portion is not significantly transmitted so the resulting lightincludes a different spectral content and thus the chromaticity valueshifts. Stated differently, because the peak of spectral emissions of B1and B2 correspond to low and high transmission portions 154 and 150, theresulting light is different in spectral content than the light emittedfrom light emitter B. Thus, in this simple example, the difference inthe chromaticity values of the unfiltered light from A and B isessentially zero and the difference in the chromaticity values in thefiltered light from A and B is not zero and may significantly impactuniformity in applications such as, for example, a display. In thisregard, the advantages of grouping light emitters according tochromaticity values that are defined after modification from atransmissive component are realized.

Reference is now made to FIGS. 5A and 5B, which are block diagramsillustrating operations for applying a filter function to light emitterchromaticity data according to some embodiments of the presentinvention. A light emitter 100 may be tested by a spectroscopic system170 to determine a spectral power distribution. The spectral powerdistribution may be used to estimate tristimulus values, which may thenbe used to estimate chromaticity data.

A spectroscopic system 170 may include a driver 172 that is configuredto drive the light emitter 100. Responsive to the driver 172, the lightemitter 100 emits unfiltered light 102 which may be received by areceiver 174. The receiver 174 may generate data 174 a corresponding toa spectral power distribution of the light emitter 100. In someembodiments, the receiver 174 may be configured to measure the spectralenergy at multiple intervals of wavelengths between 380 nm and 780 nm,which generally define the visible spectrum. In some embodiments, thereceiver 174 may provide source values 174 a corresponding to thespectral power distribution of the light from the light emitter 100.Although the receiver 174 is generally presented as a unitary component,in some embodiments, the receiver 174 may include components forreceiving, processing, storing and/or transmitting spectral powerdistribution data 174 a in raw, intermediate and/or final states.

A filter function 176 is applied to the spectral power distribution data174 a that is generated by the receiver 174. In some embodiments, thefilter function 176 may be a numerical and/or mathematical expressionthat may be used to define and/or characterize the filtering effects oftransmissive devices. For example, the filter function 176 may includefiltering effects corresponding to an LCD cell, films such as BEF and/orDBEF, light guide plates (LGP), the color filter array (CFA),polarizers, diffusers and/or other transmissive components that maytransmit and/or modify the emitted light. In some embodiments, thefilter function 176 may be expressed as spectral transmittance as adiscrete function of wavelength and may include multiple valuescorresponding to a wavelength range from 380 nm to 780 nm, for example.

A filter function 176 corresponding to an LCD cell that includes red,green and blue subpixels may be configured to compensate for relativedifferences in subpixel areas and/or fill factors. For example, a pixelmay devote 50% of the pixel area to a green subpixel and 25% of thepixel area to each of the red and blue subpixels. In some embodiments,the subpixel weighting may be accounted for by measuring bulk lighttransmittance over a broad surface of the LCD cell that includes manypixels. In this manner, the average spectral transmittance of areas ofthe LCD cell equal or larger than an area of a single pixel may bedetermined over the range of wavelengths comprising the visiblespectrum.

Application of the filter function 176 may be accomplished bymultiplying and/or convolving the source values determined by thereceiver 174 with the filter function 176 to determine a filteredspectral power distribution 176 a. In some embodiments, the filteredspectral power distribution may correspond to a front of screen spectralpower distribution of the emitter as used in the device corresponding tothe filter function 176. The filtered spectral power distribution 176 a,as computed from unfiltered spectral power distribution data 174 a andform the filter function 176, may be expressed as:

${{{Fos}\left\lbrack \underset{380}{\overset{780}{\lambda}} \right\rbrack} = {{S\left\lbrack \underset{380}{\overset{780}{\lambda}} \right\rbrack} \times {F\left\lbrack \underset{380}{\overset{780}{\lambda}} \right\rbrack}}};$where Fos is the filtered spectral power distribution 176 a thatcorresponds to, for example, the filtered light at the front of thescreen and includes data at intervals of wavelengths from 380 nm to 780nm. S is the source spectral power distribution 174 a that is receivedby the receiver and F is the filter function 176 that is applied to thesource spectral power distribution.

The filtered spectral power distribution 176 a may be used by achromaticity value generator 178 to determine filtered chromaticity datacorresponding to the light emitter 100 in the context of thetransmissive components. The chromaticity data may be estimated bycalculating filtered tristimulus values X′, Y′ and Z′ by substitutingthe filtered spectral power distribution data (Fos) 176 a for the sourcespectral power distribution (S) 174 a into the tristimulus equations.The filtered chromaticity values x′,y′ may then be calculated from thefiltered tristimulus values. In this manner, the chromaticitycoordinates x′,y′ may be determined as a function of the front of screenand/or displayed light characteristics. The chromaticity coordinatesx′,y′ may then be used to select, group and/or bin the light emitters100 according to the filtered spectral power data.

Referring to FIG. 5B, a spectroscopic system 171 may include a driver172 that is configured to drive the light emitter 100. Responsive to thedriver 172, the light emitter 100 emits unfiltered light 102, which maybe received by a filter element 180. In contrast with using amathematical and/or numerical filter function applied to raw data, someembodiments use a physical filter element 118 that filters theunfiltered light 102. The filter element 180 may include a standardizedphysical sample and/or standard corresponding to, for example, an LCDdisplay. In this regard, the filter element 180 may be a nominalreference cell that is substantially the same in spectral properties asthe LCD cell for which the light emitter 100 is intended to be used.Differences between the filter element 180 and the LCD that the filterelement 180 approximates include packaging and size, among others. Forexample, in some embodiments, the filter element 180 may be in the rangebetween 25 mm and 75 mm square or a similarly sized diameter in the caseof a circular filter element 180.

In application, the filter element 180 may be energized to a maximumstate of transparency to realize the physical filtering effects of theLCD display. In this manner, the filtered light 182 that represents theconvolution of the filter function with the source spectral data may betransmitted as filtered light 182 to the receiver 174.

The receiver 174 may generate data corresponding to a spectral powerdistribution of the filtered light 182. In some embodiments, thereceiver 174 may be configured to measure the spectral energy atmultiple intervals of wavelengths between 380 nm and 780 nm, whichgenerally define the visible spectrum. In some embodiments, the receiver174 is configured to provide values corresponding to a spectral powerdistribution of the filtered light 182. Although the receiver 174 isgenerally described as a unitary component, in some embodiments, thereceiver 174 may include distinct and/or integrated components forreceiving, processing, storing and/or transmitting spectral powerdistribution data in a raw, intermediate and/or final state.

The filtered spectral power distribution may be used by a chromaticityvalue generator 178 to determine filtered chromaticity datacorresponding to the filtered light emitter 182. The chromaticity datamay be estimated by calculating filtered tristimulus values X′, Y′ andZ′ by substituting the filtered spectral power distribution data (Fos)for the source spectral power distribution (S) into known tristimulusequations and then calculating filtered chromaticity values x′,y′ fromthe filtered tristimulus values. In this manner, the chromaticitycoordinates x′,y′ may be determined as a function of the front of screenand/or displayed light characteristics. Although discussed in thecontext of the CIE 1931 standard, the chromaticity data may also beexpressed in terms of other color spaces such as, for example, the CIE1976 L*, a*, b* color space and/or CIE 1976 u′v′ color space, amongothers. The light emitters 100 can then be selected, grouped and/orbinned according to the filtered chromaticity values x′,y′.

Reference is now made to FIG. 6, which is a block diagram illustratingoperations for controlling light emission characteristics in a displaypanel according to some embodiments of the present invention. In someembodiments, controlling light emission characteristics may includeimproving uniformity of light transmitted from the display. In someembodiments, controlling light emission characteristics may includeproviding specific chromaticity variance and/or non-uniformity othercharacteristics of the displayed light that may be affected via themethods, apparatus, systems, and/or computer program products describedherein. Some embodiments include selecting multiple light emitters as afunction of the transmissive properties of a transmissive panel and afunction of the raw spectral properties of the light emitters. Someembodiments may optionally provide that a filter function correspondingto a display is estimated (block 210). In some embodiments, estimating afilter function may include measuring the display panel prior to anintended time of use. The filter function may include data correspondingto how a spectral power distribution of received light is modified asthe light is transmitted through the display and/or any transmissivecomponents therein. For example, the filter function may include datasuch as spectral transmittance, among others, corresponding to multipleintervals of wavelengths within the visible spectrum. The display panelmay include any combination of a variety of transmissive and/orselectively transmissive components. For example, the display panel mayinclude an LCD) cell, a color filter array, a BEF and/or DBEF film,light guide panel (LGP), one or more polarizers and/or othertransmissive components among others. In some embodiments, the displaymay include a liquid crystal module (LCM) and/or a backlight unit (BLU).

Some embodiments provide that light emitters are selected as a functionof light emitted from the display panel (block 212). In someembodiments, light emitters may be selected based on a filter functioncorresponding to a display panel. In such embodiments, the spectral datacorresponding to unfiltered emitters may also be used in the selectionof the light emitters. In some embodiments, selecting the light emittersmay include generating filtered chromaticity data corresponding to eachof the light emitters. In some embodiments, the filtered chromaticitydata may be generated by applying a standardized filter to aspectroscopic system that is used to generate the filtered chromaticitydata. In some embodiments, the standardized filter corresponds to thefilter function. Selecting the light emitters may also includeestablishing a range of filtered chromaticity data and selecting theemitters within the range of filtered chromaticity data.

In some embodiments, the light emitters may include solid state lightemitters. Solid state light emitters may include white light emitterssuch as, for example, blue emitting LED's with a wavelength conversionphosphor coating and/or groups of LED's that are configured to emitlight having dominant wavelengths corresponding to red, green, yellow,cyan, orange and/or blue colors. In some embodiments, the light emittersmay be cold cathode fluorescent lamps. By selecting the light emittersas a function of light emitted from the display, front-of-screenuniformity may be increased.

Reference is now made to FIG. 7, which is a block diagram illustratingoperations for selecting multiple light emitters, as discussed aboveregarding FIG. 6, according to some embodiments of the presentinvention. Selecting light emitters (block 212) may include generatingraw spectral power distribution data corresponding to each light emitter(block 220). The raw chromaticity data may be generated using aspectroscopic device that is configured to drive the light emitter andreceive emitted light. The emitted light may be characterized in termsof a spectral power distribution across the visible spectrum, forexample.

After the raw spectral data is generated, filtered chromaticity data maybe generated (block 222). Reference is now made to FIG. 8, which is ablock diagram illustrating operations for generating filteredchromaticity data (block 222), as discussed above regarding FIG. 7,according to some embodiments of the present invention. Filteredspectral power distribution data for the light emitters is generated(block 230). In some embodiments, the filtered spectral powerdistribution data may be generated by convolving and/or multiplying theraw spectral power distribution data with the filter function tonumerically estimate the spectral power distribution data correspondingto light transmitted through the filter, display, and/or transmissivecomponents. The filtered spectral power distribution data may be used toestimate filtered light tristimulus values X′, Y′ and A′ (block 232).The filtered tristimulus values X′, Y′ and Z′ may be used to calculatefiltered chromaticity data corresponding to the chromaticity of thelight transmitted though the filter, display and/or transmissivecomponents (block 234). For example, chromaticity x′,y′ values may becalculated using the filtered tristimulus values X′, Y′, and Z′. In thismanner, the light emitters may be grouped and/or binned according to theproperties of the emitters and the filtering characteristics of a devicein which they will be used.

Reference is now made to FIG. 9, which is a block diagram illustratingoperations for increasing display uniformity according to someembodiments of the present invention. A filter function of at least onetransmissive display component is estimated (block 240). In someembodiments, the filter function may be estimated, for example, in termsof multiple intervals of wavelengths across the visible spectrum. Forexample, the filter function may be expressed as an array correspondingto intervals of wavelengths in the range between 380 nm and 780 nm. Thenumber of array elements may be varied to provide more or lessgranularity in the spectral data as needed. For example, in someembodiments, the array may include an element for every 0.5 nm step from380 nm to 780 nm. In some embodiments, the array may include an elementfor every 1.0 nm step from 380 nm to 780 nm.

Filtered chromaticity data is estimated for each of a plurality of lightemitters (block 242). In some embodiments, the filtered chromaticitydata may include generating spectral data via a filter that correspondsto the filter function. In some embodiments, the filtered chromaticitydata may include numerically and/or mathematically applying the filterfunction to raw spectral data corresponding to the light emitters.

The light emitters may be grouped according to the filtered chromaticitydata (block 244). For example, light emitters including filteredchromaticity data within defined ranges and/or bins may be groupedtogether to improve the uniformity of the light transmitted through thedisplay components. A portion of the light emitters corresponding to agroup and/or bin are selected for use in a backlight unit in the backlitdisplay panel (block 246). Although presented in the context of abacklight unit, the methods disclosed herein are applicable to edgelitdisplays and edgelight units used therein.

Referring back to FIG. 1, devices as disclosed herein may includemultiple light emitters 100 that include a first chromaticity differencecorresponding to the difference in chromaticity of unfiltered light 102emitted from the multiple light emitters. The multiple light emittersmay also include a second chromaticity difference corresponding to thedifference in chromaticity of filtered light 122, such that the secondchromaticity difference is less than the first chromaticity difference.In some embodiments, devices may include an optical element 120 thatcorresponds to the filter function and receives the unfiltered light102. The optical element 120 may also be configured to transmit filteredlight 122 corresponding to the chromaticity and/or spectral propertiesof the unfiltered light 102 and the optical element.

Reference is now made to FIG. 10, which is a schematic diagram of a sideview of a device according to some embodiments of the present invention.The multiple light emitters 100 may be supported by a backlight unithousing 124 and/or components thereof. In some embodiments, thebacklight unit housing 124 may include additional optical andnon-optical components. For example, the backlight unit housing 124 mayinclude one or more diffusers and/or reflectors and/or structuralfeatures for mounting such components.

Reference is now made to FIG. 11, which is a schematic diagram of a sideview of a device according to other embodiments of the presentinvention. Some embodiments may include a fixture housing 128 and/orcomponents thereof that are configured to support the multiple lightemitters 100 in a light fixture. In some embodiments, the opticalelement includes a lighting diffuser 126.

Reference is now made to FIG. 12, which is a schematic diagram of adevice according to yet other embodiments of the present invention. Someembodiments include a support/retention structure 129 that is configuredto support the multiple light emitters 100 during transportation,storage and/or dispensing. For example, a support/retention structure129 may include a tape and/or reel configured to receive, support,store, and/or dispense the multiple light emitters 100. In this regard,the multiple light emitters that are selected, grouped and/or binnedaccording to filtered chromaticity may be provided in commerciallybeneficial packaging. In some embodiments, a support/retention structure129 may include a rigid and/or flexible printed circuit board (PCB)strip on which multiple light emitters 100 are mounted prior to use.

Reference is now made to FIG. 13, which is a block diagram illustratingan apparatus for selecting light emitters based on intended useaccording to some embodiments of the present invention. A selectingapparatus 260 includes a filter application module 262 that isconfigured to apply a filter function to raw spectral data correspondingto each of multiple light emitters. The filter function may correspondto one or more transmissive components through which emitted light maybe transmitted. The one or more transmissive components may correspondto an intended use for the light emitters. In this manner, the filterapplication module 262 may be configured to generate filtered spectraldata corresponding to each of the light emitters.

A selecting apparatus 260 may include a chromaticity module 264 that isconfigured to estimate chromaticity values corresponding to each of thelight emitters. The chromaticity values may be determined using thefiltered spectral data that is generated by the filter applicationmodule.

Some embodiments of a selecting apparatus 260 may optionally include apower module 266 that is configured to provide power to each of thelight emitters. In some embodiments, the power module may be configuredto provide power across a range of power levels.

A selecting apparatus 260 may optionally include a spectrometric module268 that is configured to estimate the raw spectral data correspondingto each of the light emitters. The raw spectral data may be used by thefilter application module 262 to estimate the filtered spectral data. Aselecting apparatus 260 may optionally include a sorting module 270 thatis configured to sort the light emitters into multiple bins and/orgroups corresponding to chromaticity values that may be generated in thechromaticity module 264.

In addition to using the filtered spectral data for sorting and/orgrouping light emitters, the inventors discovered further techniques forreducing non-uniformity within groups of light emitters. In someembodiments, such techniques may be used in isolation and/or incombination with the techniques discussed above.

Reference is now made to FIG. 14, which is a block diagram illustratingoperations for groupings light emitters according to some embodiments ofthe present invention. Operations include selecting light emitters usinga multiple axis color space region including major and minor axes (block300). The multiple axis color space may be configured to represent eachof multiple colors as, for example, two chromaticity coordinates. Asdiscussed above, examples of a multiple axis color space may include amathematically defined color space such as the CIE 1931 color space,which defines color in terms of chromaticity. According to the CIE 1931color space, chromaticity may be expressed in terms of x, y parametersand luminance may be represented by Y, which is approximatelycorrelative of the brightness. In addition to the CIE 1931 color space,the chromaticity data may be expressed in terms of other color spacessuch as, for example, the CIE 1976 L*, a*, b* color space and/or CIE1976 L′, u′, v′ color space, among others. Some embodiments provide thatthe light emitters may include solid-state light emitter, incandescentlights and/or cold-cathode fluorescent lights.

The CIE 1931 color space is a substantially non-uniform color space andthus bin regions that are substantially equal in area may includeundesirable chromaticity differences as perceived that otherwise mightbe eliminated using a different approach. In this regard, the CIE 1976L, u′, v′ color space is a more perceptually uniform color space andthus light emitters characterized, binned and/or grouped therein mayimprove effective uniformity. In some embodiments, the CIE 1976 L, u′,v′ color space may be used in combination with the filtered spectraldata corresponding to FOS data.

Some embodiments provide that further optimization may provide improveduniformity within a constraint of reducing and/or minimizing the numberof bins by determining ideal bin sizes, geometries, orientations and/oraspect ratios. In this regard, it was discovered that Macadams ellipsesrepresented in the 1976 L, u′, v′, color space close to CIE StandardIlluminant D65 (“D65”) include specific aspect ratios and orientationsthat may improve uniformity of emitters within groups defined therein.Two points in a two-dimensional chromaticity space are considered tohave about the same chromaticity if one point is within a seven stepMacadam ellipse of the other point or vice versa. A Macadam ellipse is aclosed re-ion around a center point in a two-dimensional chromaticityspace that encompasses all points that are visually indistinguishablefrom the center point. A seven-step Macadam ellipse captures points thatare indistinguishable to an ordinary observer within seven standarddeviations.

Accordingly, some embodiments may include geometries having similaraspect ratios and can be configured to map multiple non-overlappingregions. For example, rectangular and/or elongated hexagonal shaped binsincluding aspect ratios consistent with the aspect ratios andorientations of the Macadams ellipses may improve uniformity of emitterswithin the groups defined therein. In this manner, a substantial portionof the u′, v′ color space may be defined using substantially uniform binshapes and/or sizes while reducing a bin count and limiting the emitternon-uniformity within each group. The ratio, shape and/or size may varydepending on the application specific uniformity requirements.

In some embodiments, the region includes an elliptical, quadrilateraland/or hexagonal geometry. Some embodiments provide that a regionincluding a quadrilateral geometry may include a parallelogram.

Some embodiments provide that the major axis may have a first length andthe minor axis may have a second length that is less than the firstlength. In some embodiments, a ratio of the first length to the secondlength may include a ratio in a range from 1.3 to 2.3. Some embodimentsprovide that the ratio of the first length to the second length isapproximately 2.1.

In some embodiments, the major axis of the region may be oriented atsome angle relative to a vertical axis of the multiple axis color space.Some embodiments provide that the major axis of the region may beoriented substantially ten degrees from the vertical axis of themultiple axis color space.

In some embodiments, selecting the light emitters may include selectingthe light emitters as a function of an application specific transmissioncharacteristic of an environment in which the light emitters aredesignated to be used. For example, in some embodiments, an applicationspecific transmission characteristic may include a transmissioncharacteristic of a display panel.

Operations may include generating emitter spectral power distributiondata for each of the light emitters (block 306). In some embodiments,emitter spectral distribution data may be used to select one of multipleadjacent regions corresponding to the emitter spectral powerdistribution of each of the light emitters (block 302). For example,some embodiments provide that the multiple axis color space may besubdivided into multiple adjacent regions that correspond to differentchromaticity data. In some embodiments, the regions may correspond to achromaticity center point and may be defined by boundary functions. Inthis regard, each of the light emitters may be grouped into one of themultiple regions corresponding to the spectral power distribution datathat may include chromaticity and/or luminosity.

Reference is now made to FIG. 15, which is a block diagram illustratingoperations for grouping light emitters according to some embodiments ofthe present invention. Operations include generating raw spectral powerdistribution data for each of the light emitters (block 310). Someembodiments include estimating front of screen (FOS) spectral powerdistribution data for each light emitter (block 312). In someembodiments, the FOS spectral power distribution data may be estimatedby combining an application specific transmission characteristic withthe raw spectral power distribution data of each of the light emitters.

Operations may include grouping emitters into regions of a multiple axiscolor space that include a major axis and a minor axis (block 314). Themultiple axis color space may be configured to represent each of aplurality of colors as at least two chromaticity coordinatescorresponding to the FOS spectral power distribution data of each of thelight emitters. In some embodiments, the major axis of each of theregions may include a first length and the minor axis of each of theregions may include a second length that is less than the first length.

Some embodiments provide that the major axis is oriented substantiallydifferent than a vertical axis of the multiple axis color space. In someembodiments, the major axis is oriented substantially ten degreesclockwise from the vertical axis of the multiple axis color space. Someembodiments provide that a ratio of the first length to the secondlength is in a range from 1.3 to 2.3. In some embodiments, the ratio maybe approximately 2.1.

Reference is now made to FIGS. 16A-C, which are schematic graphsillustrating regions in a multiple axis color space according to someembodiments of the present invention. Referring to FIG. 16A, a multipleaxis color space 400 is defined in terms of u′, v′ coordinates, such as,for example, in a CIE 1976 L, u′, v′ color space. In this regard, thegraph may include a u′ axis 404 and a v′ axis 402. A quadrilateralregion 410 in the multiple axis color space 400 may be defined in termsof a center point and/or one or more boundary values, equations, and/orfunctions. The quadrilateral region 410 includes a major axis 412 havinga first length and a minor axis 414 having a second length that is lessthan the first length. In some embodiments, the quadrilateral region 410may be oriented such that the major axis 412 may be angularly displacedfrom the vertical v′ axis 402. Some embodiments provide that the angulardisplacement 416 is approximately ten degrees. In some embodiments, thequadrilateral region 410 may be a parallelogram, including for example,a rectangle.

Referring to FIG. 16B, an elliptical region 420 in the multiple axiscolor space 400 may be defined in terms of a center point and/or one ormore boundary values, equations and/or functions. In some embodiments,the elliptical region 420 may include the major axis 412 and minor axis414 having first and second length characteristics similar to thequadrilateral region 410 discussed above. Some embodiments provide thatthe elliptical region 420 may be oriented to provide a similar angulardisplacement 416 as the quadrilateral region 410. Some embodimentsinclude a multiple axis color space 400 that may include a hexagonalregion 430, as illustrated in FIG. 16C.

Brief reference is now made to FIG. 17, which is a schematic graphillustrating multiple adjacent regions 440A-D in a multiple axis colorspace 400 according to some embodiments of the present invention. Theregions 440A-D may be defined in terms of respective center pointsand/or boundary values, equations, and/or functions. In this mannerlight emitters that include spectral power distribution datacorresponding to different ones of the regions 440A-D may be groupedaccording, to their corresponding regions 440A-D.

In some embodiments, the regions 440A-D may be configured to definedifferent area sizes of the multiple axis color space 400 according to athe chromaticity variation ranges defined for groups of emitterscorresponding to each of the regions 440A-D. For example, if a group ofemitters includes a narrow range of chromaticity values, thencorresponding regions 440A-D may be defined to include a relativelysmall area of the multiple axis color space 400. In this regard, as thesize of the regions 440A-D decreases, the number or regions 440A-D mayincrease to group multiple light emitters having spectral powerdistribution data corresponding to a portion of multiple axis colorspace 400. Accordingly, if a group of emitters includes a wide range ofchromaticity values, then corresponding regions 440A-D may be defined toinclude a relatively large area of the multiple axis color space 400.Although the regions 440A-D are illustrated as substantiallyrectangular, as discussed above regard FIGS. 16B and 16C, regions mayinclude elliptical, hexagonal and/or polygonal geometries, among others.Some embodiments provide that combinations of regions includingdifferent geometries may define the multiple axis color space 400 toprovide specific grouping characteristics corresponding to the spectralpower distribution data of a light emitters.

Reference is now made to FIG. 18, which is a block diagram illustratingan apparatus 460 for grouping light emitters according to someembodiments of the present invention. In some embodiments, the apparatus460 includes a chromaticity module 462 that is configured to estimatethe spectral data corresponding to each of a batch and/or set of lightemitters 470. Some embodiments provide that the spectral data mayinclude chromaticity and/or luminance values, among others. In someembodiments, the apparatus 460 may optionally include a power module 468that is configured to drive the emitters 470. Some embodiments providethat the power module 468 may be configured to drive the emitters 470 atone or more currents, voltages, and/or duty cycles to generate varyingoutput levels of the emitters 470.

In some embodiments, the apparatus 460 may include a color space regiondefinition module 464 that is configured to define boundaries of a colorspace region of a multiple axis color space. Some embodiments providethat the multiple axis color space is configured to represent each of aplurality of colors as at least two chromaticity coordinates. In someembodiments, the color space region may include a major axis including afirst length and a minor axis including a second length that is lessthan the first length. In some embodiments, the color space definitionmodule 464 may be configured to define boundaries corresponding tomultiple color space regions. Some embodiments provide that the multiplecolor space regions are adjacent one another.

In some embodiments, the apparatus 460 includes a selection module thatis configured to select a portion of the light emitters 470 thatcorrespond to the color space region. Some embodiments provide that theselection module 460 may select multiple portions of the light emitters470 corresponding to multiple color space regions. In some embodiments,FOS data may be used in conjunction with the spectral data as criteriafor selecting the portion(s) of light emitters 470 corresponding to themultiple color space region(s).

In the drawings and specification, there have been disclosed typicalembodiments of the invention and, although specific teems are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation, the scope of the invention being, set forth inthe following claims.

1. A method of grouping a plurality of light emitters, comprising:selecting a first portion of the plurality of light emitters using afirst region of a multiple axis color space that includes InternationalCommission on Illumination (CIE) 1976 and that is configured torepresent each of a plurality of colors as at least two chromaticitycoordinates, the region proximate a predefined point on the multipleaxis color space and comprising a major axis including a first lengthand a minor axis including a second length that is less than the firstlength; and selecting a plurality of other portions of the plurality oflight emitters using a plurality of other regions and having asubstantially similar size and shape as the first region, at least oneof the plurality of other regions being adjacent the first region,wherein at least one of selecting the portion of the plurality of lightemitters or selecting the plurality of other portions of the pluralityof light emitters is performed using at least one processor, wherein themajor axis is oriented substantially 10 degrees clockwise from avertical axis of the multiple axis color space, and wherein the firstregion and the plurality of other regions correspond to a portion of themultiple axis color space in which chromaticity color coordinate u′ isin a range of about 0.13 to about 0.30 and chromaticity coordinate v′ isin a range of about 0.36 to about 0.55.
 2. The method of claim 1,wherein the first region comprises hexagonal geometry.
 3. The method ofclaim 1, wherein a ratio of the first length to the second length is inrange from 1.3 to 2.3.
 4. The method of claim 1, wherein a ratio of thefirst length to the second length comprises approximately 2.1.
 5. Themethod of claim 1, wherein selecting the first portion of the pluralityof light emitters comprises selecting the portion of the plurality oflight emitters as a function of an application specific transmissioncharacteristic.
 6. The method of claim 5, wherein the applicationspecific transmission characteristic includes a transmissioncharacteristic of a display panel.
 7. The method of claim 1, furthercomprising generating emitter spectral power distribution data for eachof the plurality of light emitters and selecting one of the first regionor the plurality of other regions corresponding to the emitter spectralpower distribution of each of the plurality of light emitters.
 8. Themethod of claim 1, wherein the plurality of light emitters comprisesolid-state light emitters, incandescent lights and/or cold-cathodefluorescent lights.
 9. A computer program product for grouping aplurality of light emitters, the computer program product comprising anon-transitory computer usable storage medium having computer readableprogram code embodied in the medium, the computer readable program codeconfigured to carry out the method of claim
 1. 10. A device, comprising:a first portion of a plurality of light emitters, the first portion ofthe plurality of light emitters comprising a chromaticity differencemaximum defined by a first region of a multiple axis color space thatincludes International Commission on Illumination (CIE) 1976 and that isconfigured to represent each of a plurality of colors as at least twochromaticity coordinates, the region proximate a predefined point on themultiple axis color space, the region comprising a major axis includinga first length and a minor axis including a second length that is lessthan the first length, wherein a plurality of other portions of theplurality of light emitters comprise a chromaticity difference maximumdefined by respective ones of a plurality of other regions of themultiple axis color space, wherein each of the plurality of otherregions comprises a substantially similar geometry and orientation asthe first region, wherein the major axis is oriented at an angle that issubstantially 10 degrees from a vertical axis of the multiple axis colorspace, and wherein the first region and the plurality of other regionscorrespond to a portion of the multiple axis color space in whichchromaticity color coordinate u′ is in a range of about 0.13 to about0.30 and chromaticity coordinate v′ is in a range of about 0.36 to about0.55.
 11. The device of claim 10, wherein the first region comprises anelliptical, rectangular and/or hexagonal geometry.
 12. The device ofclaim 10, wherein a ratio of the first length to the second length is inrange from 1.3 to 2.3.
 13. The device of claim 10, wherein a ratio ofthe first length to the second length comprises approximately 2.1. 14.The device of claim 10, wherein a portion of the plurality of lightemitters further comprise a maximum chromaticity difference defined as afunction of an application specific transmission characteristic thatcorresponds to a filtering property of a transmissive component.
 15. Thedevice of claim 14, wherein the transmissive component comprises adisplay panel.
 16. The device of claim 10, wherein each of the pluralityof light emitters comprises spectral power distribution data and isgrouped into one of the first region or the plurality of other regionscorresponding to the spectral power distribution data.
 17. The device ofclaim 10, wherein the plurality of light emitters comprise solid-statelight emitters, incandescent lights and/or cold-cathode fluorescentlights.
 18. Apparatus for grouping a plurality of light emitters,comprising: a chromaticity module that is configured to estimate thespectral data corresponding to each of the plurality of light emitters;a color space region definition module that is configured to defineboundaries of a color space region of a multiple axis color space thatincludes International Commission on Illumination (CIE) 1976 and that isconfigured to represent each of a plurality of colors as at least twochromaticity coordinates, the color space region corresponding to apredefined point on the multiple axis color space and including a majoraxis including a first length and a minor axis including a second lengththat is less than the first length; and a selection module that isconfigured to select at least one portion of a plurality of portions ofthe plurality of light emitters that corresponds to a respective one ofa plurality of adjacent color space regions of the multiple axis colorspace, wherein the plurality of portions of the plurality of lightemitters comprise a chromaticity difference maximum defined byrespective ones of the plurality of adjacent color space regions of themultiple axis color space, wherein each of the plurality of regionscomprises a substantially similar shape and orientation as the colorspace region in the multiple axis color space, and wherein the majoraxis is oriented substantially 10 degrees clockwise from a vertical axisof the multiple axis color space.
 19. The apparatus of claim 18, furthercomprising means for estimating front of screen (FOS) spectral datacorresponding to each of the plurality of light emitters using thespectral data corresponding to each of the plurality of light emittersand a filtering property of a transmissive component, wherein theselection module is configured to select the portion of the plurality oflight emitters that correspond to the color space region via the FOSspectral data of each of the plurality of light emitters.
 20. A methodof grouping a plurality of light emitters, comprising: generatingemitter raw spectral power distribution data for each of the pluralityof light emitters; estimating front of screen (FOS) spectral powerdistribution data for each of the plurality of light emitters from anapplication specific transmission characteristic corresponding to afiltering property of a transmissive component and the emitter rawspectral power data for each of the plurality of light emitters; andgrouping, using at least one processing device, each of the plurality oflight emitters into one of a plurality of regions of a multiple axiscolor space that includes International Commission on Illumination (CIE)1976 and that is configured to represent each of a plurality of colorsas at least two chromaticity coordinates corresponding to the FOSspectral power distribution data of each of the plurality of lightemitters, the region comprising a major axis that defines an angle ofless than 45 degrees from a vertical axis of the multiple axis colorspace and including a first length and a minor axis including a secondlength that is less than the first length, the major axis orientedsubstantially different from the vertical axis of the multiple axiscolor space.
 21. The method of claim 20, wherein the major axis isoriented substantially 10 degrees clockwise from the vertical axis ofthe multiple axis color space.
 22. The method of claim 20, wherein aratio of the first length to the second length is in range from 1.3 to2.3.
 23. The method of claim 20, wherein a ratio of the first length tothe second length comprises approximately 2.1.